Last week, Tesla Motors showed off its latest innovation -- a system that swaps battery packs out of its cars in seconds. But it's not just cool -- this new system could boost Tesla's profits.

Last week, Tesla Motors (NASDAQ:TSLA) showed off an innovation that can only be described as "cool": a system that swaps out the battery pack of the Model S and installs a new one -- in just seconds.

Tesla plans to roll this system out to its busiest recharging stations, to offer Model S owners an option to "refuel" quickly. But as Fool.com contributor John Rosevear explains in this video, Tesla isn't just doing it for the cool factor -- there are a couple of good reasons to think that this will boost Tesla's profits.